Molecular dynamics reveals H-bonding and desolvation energy changes of the Ca2+ hydration shell triggered by terahertz wave

Terahertz (THz) wave is a promising and newly developed technology in biological medicine, especially in neuro-related treatments and devices. The effects of THz waves on ion channels are being revealed. However, the effect of THz waves on Ca2+ and surrounding hydration shells has not been clearly researched yet, restricting the understanding of THz waves' effects on the Ca2+ permeation process in channel structures, such as ion channels. Thus, in this work, we carried out molecular dynamics simulations to fully explore the resonant effects of THz waves on (1) hydrogen bonding among the hydration shells of Ca2+ and (2) desolvation energy of each hydration shell while permeating through an ion channel. Our work indicates that a 14.5 THz wave will remold the hydrogen bonding pattern of the second and third hydration shells, weaken the effect of water dipole reorientation effects of the first and second hydration shells, and increase the desolvation energy of the second and third hydration shells. This work expands the method to estimate the ionic desolvation energy under specific conditions and further increases our cognitions on the effects of THz waves on the structure of the Ca2+ hydration shell and its hydrogen bond pattern.